Synthesis and Antimicrobial Activity of 2-[2-(2,6-dichloro phenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H)ones.

A series of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H) ones 6a-m have been synthesized by the reaction of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-substituted phenylacrylamido-6,8-dibromoquinazolin-4(3H) ones 5a-m with hydrazine hydrate in the presence of glacial acetic acid. The chalcones 5a-m were prepared by the condensation of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-acetamido-6,8-dibromoquinazolin-4(3H)one 4 with different substituted aromatic aldehyde. The benzoxazinone 2 was synthesized from 2-[2-(2,6-dichlorophenyl)amino]phenyl acetyl chloride 1 on treatment with 3,5-dibromoanthranilic acid in pyridine, which on reaction with hydrazine hydrate and then on acetylation reaction yielded 4. The structures of these compounds have been elucidated by elemental analyses, IR, and NMR spectral data. The title compounds pyrazolyl-quinazolin-4(3H)ones 6a-m were evaluated for their antibacterial and antifungal activities in vitro.

INTRODUCTION

The recent literature reveals that the quinazolinone moiety associated with vn class="Chemical">arious aromatic as well heterocyclic compounds possess wide range of pharmacological properties such as antibacterial,[1] antifungal,[1] analgesic,[2] anti-inflammatory,[3] anthelminthic,[4] anticonvulsant,[5] anti HIV,[6] antitubercular,[7] CNS depressant,[8] cytotoxicity,[9] diuretic,[10] and hypolipidemic[11] activities. Pyrazoline systems are known to be biologically active and are important constituents of many pharmacological products. These compounds are known for their antibacterial,[12] antifungal,[13] antimycobacterial,[14] analgesic,[15] anti-inflammatory,[16] anticancer,[17] antiamoebic,[18] molluscicidal,[19] hypotensive,[20] antinociceptive,[21] antidepressant,[22] anticonvulsant,[23] and antiviral[24] activities. The aim of the present work was to attach pyrazoline molecule to quinazolin-4(3H)one in order to find new biologically active pharmacophore. Thus, synthesis of pyrazolyl-quinazolin-4(3H)ones 6a-m has been achieved. The potency[25] of compounds 6a-m is compared with standard drugs to study the strength of compounds 6a-m, with a hope to get a better antimicrobial agent.

MATERIALS AND METHODS

The melting points were determined in open capillary tubes and n class="Chemical">are uncorrected. The infrared (IR) spectra of the synthesized compounds were recorded using KBr pellet on Perkin Elmer 1300 FTIR spectrometer and frequencies are recorded in wave number (cm-1). Nuclear magnetic resonance (1H-NMR and 13C-NMR) spectra were recorded on Bruker Avance II 400 NMR spectrometer using deutero chloroform (CDCl3) as a solvent. The chemical shifts are reported in δ (part per million) downfield from tetramethylsilane (TMS) as an internal standard. The purity of all the compounds was checked by TLC on Merck silica gel 60 F254 using toluene:ethylacetate (8:2) as mobile phase, and spots were visualized under UV radiation. 2-[(2,6-Dichlorophenyl)amino]phenyl acetyl chloride 1 was synthesized by the literature procedure.[26]

Procedure for the preparation of n class="Chemical">2-[2-(2,6-Dichlorophenyl)amino]benzyl-6,8-dibromo-3,1-benzoxazin-4(H)one (2)

A mixture of 2-[(2,6-dichlorophenyl)amino]phenyl acetyl chloride 1 (0.01 mol) and n class="Chemical">3,5-dibromo anthranilic acid (0.01 mol) in 20 ml pyridine was stirred at 0-5 °C for 1 h, further stirred for 1 h at room temperature. After completion of reaction, a pasty mass obtained and was washed thoroughly with sodium bicarbonate (5 % w/v) to remove unreacted acid. A solid separated was filtered, dried, and recrystallized from methanol.

Yield: 68%. m.p. 171-173 °C. IR (KBr) (cm-1): 3447 (NH str), 2927, 2854 (CH2str), 1748 (C=O str), 1614 (C=N str), 1150 (C-O str), 743 (n class="Chemical">C-Cl str), 565 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.55 (s, 2H, CH2), 6.37-8.15 (m, 9H, Ar-H), 9.13 (bs, 1H, NH). Anal. found: C, 45.36; H, 2.15; N, 5.07 %; Calcd. for C21H12Br2Cl2N2O2, C, 45.44; H, 2.18; N, 5.05 %.

Procedure for the preparation of n class="Chemical">3-Amino-2-[2-(2,6-Dichlorophenyl)amino]benzyl-6,8-dibromoquinazolin-4(3H)one (3)

A mixture of 2-[2-(2,6-dichlorophenyl)amino]benzyl-6,8-dibromo-3,1-benzoxazine-4(H)one 2 (0.01 mol) and n class="Chemical">hydrazine hydrate (0.01 mol) in 25 ml absolute ethanol was refluxed on water bath for 6-8 h. After completion of the reaction, it was slowly poured onto crushed ice with continuous stirring. The solid thus obtained, was filtered, and washed several times with cold water. The crude product was dried and recrystallized from ethanol.

Yield: 64%. m.p. 146-148 °C. IR (KBr) (cm-1): 3510-3393 (NH and NH2str), 2932, 2857 (CH2str), 1721 (C=O str), 1612 (C=N str), 748 (n class="Chemical">C-Cl str), 570 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.58 (s, 2H, CH2), 5.75 (bs, 2H, NH2), 6.38-8.10 (m, 9H, Ar-H), 9.15 (bs, 1H, NH). Anal. found: C, 44.25; H, 2.53; N, 9.81 %; Calcd. for C21H14Br2Cl2N4O, C, 44.32; H, 2.48; N, 9.85 %.

Procedure for the preparation of n class="Chemical">2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-acetamido-6,8-dibromoquinazolin-4(3H)one (4)

To the solution of 3-amino-2-[2-(2,6-dichlorophenyl)amino]benzyl-6,8-dibromoquinazolin-4(3H)one 3 (0.01 mol) in 50 ml dry n class="Chemical">benzene, acetyl chloride (0.01 mol) was added drop by drop at 0-5 °C over the period of 1 h with continuous shaking. After completion of the addition, the reaction mixture was kept overnight. The excess of solvent was distilled off under reduced pressure and then poured onto ice and shaken well. The solid thus obtained was filtered and recrystallized from methanol.

Yield: 69 %. m.p. 193-195 °C. IR (KBr) (cm-1): 3447 (NH str), 2935, 2859 (CH2str), 1727 (C=O str), 1645(C=O str of n class="Chemical">amide), 1615 (C=N str), 753 (C-Cl str), 573 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 2.23 (s, 3H, CH3), 3.53 (s, 2H, CH2), 6.37-8.12 (m, 9H, Ar-H), 9.14 (bs, 1H, NH), 10.32 (bs, 1H, NH). Anal. found: C, 45.28; H, 2.61; N, 9.15 %; Calcd. for C23H16Br2Cl2N4O2, C, 45.20; H, 2.64; N, 9.17 %.

General procedure for the preparation of 2-[2-(2,6-Din class="Chemical">chlorophenyl)amino]benzyl-3-(substituted phenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5a-m)

To the solution of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-acetamido-6,8-dibromoquinazolin-4(3H)one 4 (0.01 mol) in 50 ml absolute n class="Chemical">ethanol, benzaldehyde (0.01 mol) in 2 % NaOH was added and refluxed for 10-12 h. After completed the reaction, it was concentrated, cooled, and poured onto ice. The solid thus obtained was filtered, washed with water, and recrystallized from methanol. The remaining compounds 5b-m were synthesized by using the same procedure.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(phenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5a)

Yield: 67 %. m.p. 146-148 °C. IR (KBr) (cm-1): 3441 (NH str), 2921, 2852 (CH2str), 1719 (C=O str), 1613 (C=N str), 1576 (CH=CH str), 749 (n class="Chemical">C-Cl str), 578 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.56 (s, 2H, CH2), 6.39-8.16 (m, 14H, Ar-H), 6.80 (d, 1H, =CHCO, J = 16 Hz), 7.62 (d, 1H, =CH-Ar, J = 16 Hz), 8.84 (bs, 1H, CONH), 9.18 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.57 (CH2), 112.37-148.53 (26C, CH=CH and Ar-C), 162.06 (C=O), 168.25 (C=N), 173.12 (CONH). Anal. found: C, 51.46; H, 2.92; N, 8.04 %; Calcd. for C30H20Br2Cl2N4O2, C, 51.53; H, 2.88; N, 8.01%.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(2-hydroxyphenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5b)

Yield: 72%. m.p. 156-158 °C. IR (KBr) (cm-1): 3547 (OH str), 3438 (NH str), 2926, 2854 (CH2str), 1722 (C=O str), 1617 (C=N str), 1566 (CH=CH str), 757 (n class="Chemical">C-Cl str), 573 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.54 (s, 2H, CH2), 6.37-8.13 (m, 13H, Ar-H), 6.78 (d, 1H, =CHCO, J = 16.2 Hz), 7.59 (d, 1H, =CH-Ar, J = 16.2 Hz), 8.82 (bs, 1H, CONH), 9.16 (bs, 1H, NH), 10.36 (bs, 1H, OH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.63 (CH2), 112.23-155.67 (26C, CH=CH and Ar-C), 161.82 (C=O), 168.40 (C=N), 173.22 (CONH). Anal. found: C, 50.35; H, 2.86; N, 7.79 %; Calcd. for C30H20Br2Cl2N4O3, C, 50.38; H, 2.82; N, 7.83 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(3-hydroxyphenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5c)

Yield: 66%. m.p. 171-173 °C. IR (KBr) (cm-1): 3542 (OH str), 3450 (NH str), 2930, 2855 (CH2str), 1726 (C=O str), 1612 (C=N str), 1575 (CH=CH str), 752 (n class="Chemical">C-Cl str), 580 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.51 (s, 2H, CH2), 5.57 (bs, 1H, OH), 6.37-8.14 (m, 13H, Ar-H), 6.80 (d, 1H, =CHCO, J = 16.2 Hz), 7.63 (d, 1H, =CH-Ar, J = 16.2 Hz), 8.86 (bs, 1H, CONH), 9.15 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.60 (CH2), 112.18-159.29 (26C, CH=CH and Ar-C), 162.12 (C=O), 168.17 (C=N), 172.98 (CONH). Anal. found: C, 50.31; H, 2.77; N, 7.88 %; Calcd. for C30H20Br2Cl2N4O3, C, 50.38; H, 2.82; N, 7.83 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(4-hydroxyphenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5d)

Yield: 73 %. m.p. 184-186 °C. IR (KBr) (cm-1): 3548 (OH str), 3446 (NH str), 2934, 2853 (CH2str), 1720 (C=O str), 1609 (C=N str), 1572 (CH=CH str), 748 (n class="Chemical">C-Cl str), 581 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.58 (s, 2H, CH2), 5.59 (bs, 1H, OH), 6.38-8.12 (m, 13H, Ar-H), 6.81 (d, 1H, =CHCO, J = 16.4 Hz), 7.62 (d, 1H, =CH-Ar, J = 16.4 Hz), 8.80 (bs, 1H, CONH), 9.15 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.45 (CH2), 112.23-157.32 (26C, CH=CH and Ar-C), 161.93 (C=O), 168.03 (C=N), 173.34 (CONH). Anal. found: C, 50.42; H, 2.83; N, 7.76%; Calcd. for C30H20Br2Cl2N4O3, C, 50.38; H, 2.82; N, 7.83%.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(2-chlorophenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5e)

Yield: 72 %. m.p. 145-147 °C. IR (KBr) (cm-1): 3444 (NH str), 2922, 2846 (CH2str), 1723 (C=O str), 1614 (C=N str), 1578 (CH=CH str), 745 (n class="Chemical">C-Cl str), 583 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.55 (s, 2H, CH2), 6.37-8.13 (m, 13H, Ar-H), 6.78 (d, 1H, =CHCO, J = 16.4 Hz), 7.61 (d, 1H, =CH-Ar, J = 16.4 Hz), 8.81 (bs, 1H, CONH), 9.13 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.26 (CH2), 111.95-148.49 (26C, CH=CH and Ar-C), 162.02 (C=O), 168.18 (C=N), 173.27 (CONH). Anal. found: C, 49.20; H, 2.67; N, 7.61 %; Calcd. for C30H19Br2Cl3N4O2, C, 49.11; H, 2.61; N, 7.64 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(3-chlorophenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5f)

Yield: 65 %. m.p. 163-165 °C. IR (KBr) (cm-1): 3451 (NH str), 2926, 2849 (CH2str), 1718 (C=O str), 1611 (C=N str), 1580 (CH=CH str), 755 (n class="Chemical">C-Cl str), 580 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.52 (s, 2H, CH2), 6.38-8.15 (m, 13H, Ar-H), 6.82 (d, 1H, =CHCO, J = 16.2 Hz), 7.60 (d, 1H, =CH-Ar, J = 16.2 Hz), 8.79 (bs, 1H, CONH), 9.16 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.42 (CH2), 112.08-148.36 (26C, CH=CH and Ar-C), 161.87 (C=O), 167.92 (C=N), 173.14 (CONH). Anal. found: C, 49.06; H, 2.57; N, 7.68 %; Calcd. for C30H19Br2Cl3N4O2, C, 49.11; H, 2.61; N, 7.64 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(4-chlorophenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5g)

Yield: 69 %. m.p. 176-178 °C. IR (KBr) (cm-1): 3447 (NH str), 2930, 2855 (CH2str), 1716 (C=O str), 1610 (C=N str), 1576 (CH=CH str), 744 (n class="Chemical">C-Cl str), 571 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.58 (s, 2H, CH2), 6.37-8.13 (m, 13H, Ar-H), 6.84 (d, 1H, =CHCO, J = 16 Hz), 7.60 (d, 1H, =CH-Ar, J = 16 Hz), 8.82 (bs, 1H, CONH), 9.17 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.55 (CH2), 112.12-148.59 (26C, CH=CH and Ar-C), 162.14 (C=O), 167.88 (C=N), 173.03 (CONH). Anal. found: C, 49.17; H, 2.65; N, 7.58 %; Calcd. for C30H19Br2Cl3N4O2, C, 49.11; H, 2.61; N, 7.64 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(2-nitrophenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5h)

Yield: 70%. m.p. 202-204°C. IR (KBr) (cm-1): 3454 (NH str), 2932, 2856 (CH2str), 1723 (C=O str), 1615 (C=N str), 1582 (CH=CH str), 1544, 1361 (n class="Chemical">NO2str), 745 (C-Cl str), 577 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.54 (s, 2H, CH2), 6.38-8.16 (m, 13H, Ar-H), 6.83 (d, 1H, =CHCO, J = 16.2 Hz), 7.62 (d, 1H, =CH-Ar, J = 16.2 Hz), 8.81 (bs, 1H, CONH), 9.16 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.38 (CH2), 112.06-150.29 (26C, CH=CH and Ar-C), 162.25 (C=O), 168.04 (C=N), 172.91 (CONH). Anal. found: C, 48.36; H, 2.52; N, 9.46%; Calcd. for C30H19Br2Cl2N5O4, C, 48.42; H, 2.57; N, 9.41%.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(3-nitrophenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5i)

Yield: 68%. m.p. 227-229°C. IR (KBr) (cm-1): 3453 (NH str), 2930, 2856 (CH2str), 1722 (C=O str), 1606 (C=N str), 1576 (CH=CH str), 1538, 1356 (n class="Chemical">NO2str), 741 (C-Cl str), 573 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.52 (s, 2H, CH2), 6.37-8.40 (m, 13H, Ar-H), 6.82 (d, 1H, =CHCO, J = 16 Hz), 7.64 (d, 1H, =CH-Ar, J = 16 Hz), 8.84 (bs, 1H, CONH), 9.15 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.35 (CH2), 112.23-150.44 (26C, CH=CH and Ar-C), 161.98 (C=O), 168.28 (C=N), 172.84 (CONH). Anal. found: C, 48.34; H, 2.60; N, 9.43%; Calcd. for C30H19Br2Cl2N5O4, C, 48.42; H, 2.57; N, 9.41%.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(4-nitrophenylacrylamido)-6,8-dibromoquinazolin-4(3H)ones (5j)

Yield: 63%. m.p. 238-239°C. IR (KBr) (cm-1): 3446 (NH str), 2932, 2857 (CH2str), 1726 (C=O str), 1608 (C=N str), 1585 (CH=CH str), 1543, 1362 (n class="Chemical">NO2str), 756 (C-Cl str), 582 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.58 (s, 2H, CH2), 6.38-8.16 (m, 13H, Ar-H), 6.80 (d, 1H, =CHCO, J = 16.2 Hz), 7.61 (d, 1H, =CH-Ar, J = 16.2 Hz), 8.82 (bs, 1H, CONH), 9.16 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.57 (CH2), 112.18-148.24 (26C, CH=CH and Ar-C), 162.21 (C=O), 168.07 (C=N), 173.22 (CONH). Anal. found: C, 48.49; H, 2.51; N, 9.37%; Calcd. for C30H19Br2Cl2N5O4, C, 48.42; H, 2.57; N, 9.41%.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(4-n class="Chemical">dimethylaminophenylacrylamido)-6,8-dibromo quinazolin-4(3H)ones (5k)

Yield: 67%. m.p. 161-163 °C. IR (KBr) (cm-1): 3448 (NH str), 2933, 2858 (CH2str), 1718 (C=O str), 1612 (C=N str), 1579 (CH=CH str), 752 (n class="Chemical">C-Cl str), 578 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 2.84 (s, 6H, N(CH3)2), 3.55 (s, 2H, CH2), 6.37-8.15 (m, 13H, Ar-H), 6.78 (d, 1H, =CHCO, J = 16.4 Hz), 7.59 (d, 1H, =CH-Ar, J = 16.4 Hz), 8.78 (bs, 1H, CONH), 9.13 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.27 (CH2), 46.64 (N-(CH3)2), 111.92-150.13 (26C, CH=CH and Ar-C), 162.14 (C=O), 168.12 (C=N), 173.06 (CONH). Anal. found: C, 51.67; H, 3.32; N, 9.47%; Calcd. for C32H25Br2Cl2N5O2, C, 51.78; H, 3.39; N, 9.43%.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(2-methoxyphenylacrylamido)-6,8-dibromo n class="Chemical">quinazolin-4(3H)ones (5l)

Yield: 65 %. m.p. 157-159 °C. IR (KBr) (cm-1): 3453 (NH str), 2928, 2850 (CH2str), 1723 (C=O str), 1615 (C=N str), 1580 (CH=CH str), 1245, 1103 (C-n class="Chemical">O-C str), 751, (C-Cl str), 570 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.52 (s, 2H, CH2), 3.65 (s, 3H, OCH3), 6.38-8.15 (m, 13H, Ar-H), 6.82 (d, 1H, =CHCO, J = 16 Hz), 7.63 (d, 1H, =CH-Ar, J = 16 Hz), 8.80 (bs, 1H, CONH), 9.18 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.64 (CH2), 61.15 (OCH3), 112.23-156.34 (26C, CH=CH and Ar-C), 162.26 (C=O), 167.79 (C=N), 173.35 (CONH). Anal. found: C, 50.92; H, 3.10; N, 7.62 %; Calcd. for C31H22Br2Cl2N4O3, C, 51.06; H, 3.04; N, 7.68 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(4-methoxyphenylacrylamido)-6,8-dibromo n class="Chemical">quinazolin-4(3H)ones (5m)

Yield: 68%. m.p. 173-175°C. IR (KBr) (cm-1): 3442 (NH str), 2923, 2849 (CH2str), 1710 (C=O str), 1609 (C=N str), 1581 (CH=CH str), 1243, 1108 (C-n class="Chemical">O-C str), 745 (C-Cl str), 569 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.51 (s, 2H, CH2), 3.66 (s, 3H, OCH3), 6.37-8.16 (m, 13H, Ar-H), 6.80 (d, 1H, =CHCO, J = 16.2 Hz), 7.58 (d, 1H, =CH-Ar, J = 16.2 Hz), 8.78 (bs, 1H, CONH), 9.16 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.57 (CH2), 59.38 (OCH3), 111.97-158.29 (26C, CH=CH and Ar-C), 161.97 (C=O), 167.86 (C=N), 173.16 (CONH). Anal. found: C, 51.14; H, 3.01; N, 7.67%; Calcd. for C31H22Br2Cl2N4O3, C, 51.06; H, 3.04; N, 7.68%.

General procedure for the preparation of 2-[2-(2,6-Din class="Chemical">chlorophenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro-1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H)ones (6a-m)

A mixture of 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-(phenylacrylamido)-6,8-dibromo n class="Chemical">quinazolin-4(3H)one 5a (0.01 mol) and hydrazine hydrate (0.01 mol) in 30 ml absolute methanol was added few drops of glacial acetic acid and refluxed for 8-10 h. After completion of the reaction, excess of solvent was distilled off; the separated solid was filtered, washed with water, and recrystallized from methanol. Similarly other pyrazolyl derivatives 6b-m were synthesized.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-(5-phenyl-4,5-dihydro-n class="Chemical">1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H)ones (6a)

Yield: 58 %. m.p. 133-135 °C. IR (KBr) (cm-1): 3443 (NH str), 2924, 2853 (CH2str), 1727 (C=O str), 1612 (C=N str), 747 (n class="Chemical">C-Cl str), 575 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.04 (dd, 1H, Ha, Ja,b = 17.4 Hz, Jax = 5.5 Hz), 3.47 (dd, 1H, Hb, Jba = 17.4 Hz, Jbx = 12 Hz), 3.54 (s, 2H, CH2), 5.49 (dd, 1H, Hx, Jxb = 12 Hz, Jxa= 5.5 Hz), 6.38-8.15 (m, 15H, NH and Ar-H), 8.35 (bs, 1H, NH), 9.17 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.46 (CH2), 36.42 (CH2of pyrazole), 55.57 (CH of pyrazole), 112.43-148.57 (24C, Ar-C), 161.17 (C=N of pyrazole), 162.15 (C=O), 168.34 (C=N). Anal. found: C, 50.46; H, 3.08; N, 11.72 %; Calcd. for C30H22Br2Cl2N6O, C, 50.52; H, 3.11; N, 11.78 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(2-hydroxyphenyl)-4,5-dihydro-n class="Chemical">1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6b)

Yield: 62 %. m.p. 149-151 °C. IR (KBr) (cm-1): 3543 (OH str), 3440 (NH str), 2927, 2853 (CH2str), 1732 (C=O str), 1607 (C=N str), 755 (n class="Chemical">C-Cl str), 578 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.02 (dd, 1H, Ha, Ja,b= 17.4 Hz, Jax= 5.5 Hz), 3.45 (dd, 1H, Hb, Jba= 17.4 Hz, Jbx= 11.9 Hz), 3.56 (s, 2H, CH2), 5.48 (dd, 1H, Hx, Jxb= 11.9 Hz, Jxa= 5.5 Hz), 6.37-8.14 (m, 14H, NH and Ar-H), 8.42 (bs, 1H, NH), 9.15 (bs, 1H, NH), 10.35 (bs, 1H, OH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.60 (CH2), 35.41 (CH2of pyrazole), 55.65 (CH of pyrazole), 112.19-155.63 (24C, Ar-C), 161.21 (C=N of pyrazole), 161.94 (C=O), 168.29 (C=N). Anal. found: C, 49.38; H, 3.03; N, 11.54 %; Calcd. for C30H22Br2Cl2N6O2, C, 49.41; H, 3.04; N, 11.52 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(3-hydroxyphenyl)-4,5-dihydro-n class="Chemical">1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6c)

Yield: 67 %. m.p. 162-163 °C. IR (KBr) (cm-1): 3540 (OH str), 3453 (NH str), 2928, 2854 (CH2str), 1730 (C=O str), 1609 (C=N str), 750 (n class="Chemical">C-Cl str), 578 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.05 (dd, 1H, Ha, Ja,b= 17.6 Hz, Jax= 5.4 Hz), 3.46 (dd, 1H, Hb, Jba= 17.6 Hz, Jbx= 12 Hz), 3.53 (s, 2H, CH2), 5.48 (dd, 1H, Hx, Jxb= 12 Hz, Jxa= 5.4 Hz), 5.59 (bs, 1H, OH), 6.37-8.15 (m, 14H, NH and Ar-H), 8.37 (bs, 1H, NH), 9.14 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.48 (CH2), 36.53 (CH2of pyrazole), 54.98 (CH of pyrazole), 112.23-159.33 (24C, Ar-C), 161.13 (C=N of pyrazole), 162.26 (C=O), 168.09 (C=N). Anal. found: C, 49.33; H, 3.08; N, 11.55 %; Calcd. for C30H22Br2Cl2N6O2, C, 49.41; H, 3.04; N, 11.52 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(4-hydroxyphenyl)-4,5-dihydro-n class="Chemical">1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6d)

Yield: 63 %. m.p. 177-179 °C. IR (KBr) (cm-1): 3550 (OH str), 3448 (NH str), 2931, 2852 (CH2str), 1725 (C=O str), 1608 (C=N str), 743 (n class="Chemical">C-Cl str), 583 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.07 (dd, 1H, Ha, Ja,b= 17.4 Hz, Jax= 5.4 Hz), 3.49 (dd, 1H, Hb, Jba= 17.4 Hz, Jbx= 11.8 Hz), 3.56 (s, 2H, CH2), 5.46 (dd, 1H, Hx, Jxb= 11.8 Hz, Jxa= 5.4 Hz), 5.58 (bs, 1H, OH), 6.37-8.12 (m, 14H, NH and Ar-H), 8.40 (bs, 1H, NH), 9.17 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.39 (CH2), 36.51 (CH2of pyrazole), 55.62 (CH of pyrazole), 112.18-157.38 (24C, Ar-C), 161.34 (C=N of pyrazole), 162.04 (C=O), 167.97 (C=N). Anal. found: C, 49.46; H, 3.05; N, 11.48 %; Calcd. for C30H22Br2Cl2N6O2, C, 49.41; H, 3.04; N, 11.52 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(2-n class="Chemical">chlorophenyl)-4,5-dihydro-1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6e)

Yield: 59 %. m.p. 143-145 °C. IR (KBr) (cm-1): 3442 (NH str), 2924, 2847 (CH2str), 1720 (C=O str), 1611 (C=N str), 741 (n class="Chemical">C-Cl str), 585 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.02 (dd, 1H, Ha, Ja,b= 17.2 Hz, Jax= 5.5 Hz), 3.46 (dd, 1H, Hb, Jba= 17.2 Hz, Jbx= 12 Hz), 3.54 (s, 2H, CH2), 5.48 (dd, 1H, Hx, Jxb= 12 Hz, Jxa= 5.5 Hz), 6.38-8.14 (m, 14H, NH and Ar-H), 8.38 (bs, 1H, NH), 9.15 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.32 (CH2), 36.46 (CH2of pyrazole), 55.56 (CH of pyrazole), 112.03-148.57 (24C, Ar-C), 161.25 (C=N of pyrazole), 162.13 (C=O), 168.10 (C=N). Anal. found: C, 48.12; H, 2.81; N, 11.25 %; Calcd. for C30H21Br2Cl3N6O, C, 48.19; H, 2.83; N, 11.24 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(3-n class="Chemical">chlorophenyl)-4,5-dihydro-1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6f)

Yield: 67 %. m.p. 151-153 °C. IR (KBr) (cm-1): 3447 (NH str), 2926, 2850 (CH2str), 1723 (C=O str), 1613 (C=N str), 749 (n class="Chemical">C-Cl str), 579 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.04 (dd, 1H, Ha, Ja,b= 17.4 Hz, Jax= 5.5 Hz), 3.47 (dd, 1H, Hb, Jba= 17.4 Hz, Jbx= 11.8 Hz), 3.52 (s, 2H, CH2), 5.46 (dd, 1H, Hx, Jxb= 11.8 Hz, Jxa= 5.5 Hz), 6.38-8.15 (m, 14H, NH and Ar-H), 8.40 (bs, 1H, NH), 9.13 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.24 (CH2), 36.56 (CH2of pyrazole), 55.63 (CH of pyrazole), 112.17-148.66 (24C, Ar-C), 161.20 (C=N of pyrazole), 162.18 (C=O), 168.21 (C=N). Anal. found: C, 48.26; H, 2.79; N, 11.22 %; Calcd. for C30H21Br2Cl3N6O, C, 48.19; H, 2.83; N, 11.24 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(4-n class="Chemical">chlorophenyl)-4,5-dihydro-1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6g)

Yield: 63 %. m.p. 166-168 °C. IR (KBr) (cm-1): 3440 (NH str), 2921, 2848 (CH2str), 1719 (C=O str), 1608 (C=N str), 743 (n class="Chemical">C-Cl str), 575 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.06 (dd, 1H, Ha, Ja,b= 17.5 Hz, Jax= 5.4 Hz), 3.49 (dd, 1H, Hb, Jba= 17.5 Hz, Jbx= 11.9 Hz), 3.54 (s, 2H, CH2), 5.48 (dd, 1H, Hx, Jxb= 11.9 Hz, Jxa= 5.4 Hz), 6.37-8.16 (m, 14H, NH and Ar-H), 8.37 (bs, 1H, NH), 9.14 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.38 (CH2), 36.42 (CH2of pyrazole), 55.53 (CH of pyrazole), 111.98-148.57 (24C, Ar-C), 161.23 (C=N of pyrazole), 162.29 (C=O), 168.36 (C=N). Anal. found: C, 48.08; H, 2.80; N, 11.28 %; Calcd. for C30H21Br2Cl3N6O, C, 48.19; H, 2.83; N, 11.24 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(n class="Chemical">2-nitrophenyl)-4,5-dihydro-1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6h)

Yield: 69 %. m.p. 169-171 °C. IR (KBr) (cm-1): 3450 (NH str), 2928, 2852 (CH2str), 1725 (C=O str), 1612 (C=N str), 1548, 1363 (n class="Chemical">NO2str), 754 (C-Cl str), 572 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.04 (dd, 1H, Ha, Ja,b= 17.6 Hz, Jax= 5.5 Hz), 3.47 (dd, 1H, Hb, Jba= 17.6 Hz, Jbx= 12 Hz), 3.52 (s, 2H, CH2), 5.46 (dd, 1H, Hx, Jxb= 12 Hz, Jxa= 5.5 Hz), 6.39-8.16 (m, 14H, NH and Ar-H), 8.41 (bs, 1H, NH), 9.15 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.21 (CH2), 36.59 (CH2of pyrazole), 55.68 (CH of pyrazole), 112.10-150.38 (24C, Ar-C), 161.12 (C=N of pyrazole), 162.35 (C=O), 168.19 (C=N). Anal. found: C, 47.43; H, 2.75; N, 12.89 %; Calcd. for C30H21Br2Cl2N7O3, C, 47.52; H, 2.79; N, 12.93 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(3-n class="Chemical">nitrophenyl)-4,5-dihydro-1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6i)

Yield: 61 %. m.p. 187-189 °C. IR (KBr) (cm-1): 3455 (NH str), 2930, 2855 (CH2str), 1727 (C=O str), 1615 (C=N str), 1542, 1360 (n class="Chemical">NO2str), 750 (C-Cl str), 577 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.02 (dd, 1H, Ha, Ja,b= 17.5 Hz, Jax= 5.4 Hz), 3.45 (dd, 1H, Hb, Jba= 17.5 Hz, Jbx= 11.8 Hz), 3.53 (s, 2H, CH2), 5.47 (dd, 1H, Hx, Jxb= 11.8 Hz, Jxa= 5.4 Hz), 6.38-8.39 (m, 14H, NH and Ar-H), 8.42 (bs, 1H, NH), 9.17 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.27 (CH2), 36.52 (CH2of pyrazole), 55.65 (CH of pyrazole), 112.13-150.46 (24C, Ar-C), 161.05 (C=N of pyrazole), 162.23 (C=O), 168.14 (C=N). Anal. found: C, 47.45; H, 2.76; N, 12.92 %; Calcd. for C30H21Br2Cl2N7O3, C, 47.52; H, 2.79; N, 12.93 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(4-n class="Chemical">nitrophenyl)-4,5-dihydro-1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6j)

Yield: 63 %. m.p. 198-199 °C. IR (KBr) (cm-1): 3441 (NH str), 2925, 2852 (CH2str), 1729 (C=O str), 1611 (C=N str), 1540, 1363 (n class="Chemical">NO2str), 754 (C-Cl str), 587 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.05 (dd, 1H, Ha, Ja,b= 17.4 Hz, Jax= 5.4 Hz), 3.48 (dd, 1H, Hb, Jba= 17.4 Hz, Jbx= 12 Hz), 3.57 (s, 2H, CH2), 5.50 (dd, 1H, Hx, Jxb= 12 Hz, Jxa= 5.4 Hz), 6.37-8.15 (m, 14H, NH and Ar-H), 8.40 (bs, 1H, NH), 9.15 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.53 (CH2), 36.47 (CH2of pyrazole), 55.70 (CH of pyrazole), 112.24-148.39 (24C, Ar-C), 161.17 (C=N of pyrazole), 162.34 (C=O), 168.18 (C=N). Anal. found: C, 47.40; H, 2.80; N, 12.85 %; Calcd. for C30H21Br2Cl2N7O3, C, 47.52; H, 2.79; N, 12.93 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(4-n class="Chemical">dimethylaminophenyl)-4,5-dihydro-1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6k)

Yield: 60 %. m.p. 157-159 °C. IR (KBr) (cm-1): 3454 (NH str), 2935, 2857 (CH2str), 1721 (C=O str), 1616 (C=N str), 758 (n class="Chemical">C-Cl str), 568 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.06 (dd, 1H, Ha, Ja,b= 17.6 Hz, Jax= 5.5 Hz), 3.48 (dd, 1H, Hb, Jba= 17.6 Hz, Jbx= 11.9 Hz), 3.56 (s, 2H, CH2), 5.51 (dd, 1H, Hx, Jxb= 11.9 Hz, Jxa= 5.5 Hz), 6.38-8.16 (m, 14H, NH and Ar-H), 8.37 (bs, 1H, NH), 9.14 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.32 (CH2), 36.38 (CH2of pyrazole), 55.59 (CH of pyrazole), 112.15-150.27 (24C, Ar-C), 161.22 (C=N of pyrazole), 162.28 (C=O), 168.24 (C=N). Anal. found: C, 50.75; H, 3.59; N, 12.98 %; Calcd. for C32H27Br2Cl2N7O, C, 50.82; H, 3.60; N, 12.96 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(2-methoxyphenyl)-4,5-dihydro-n class="Chemical">1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6l)

Yield: 63 %. m.p. 147-149 °C. IR (KBr) (cm-1): 3440 (NH str), 2920, 2846 (CH2str), 1715 (C=O str), 1606 (C=N str), 1248, 1107 (C-n class="Chemical">O-C str), 759 (C-Cl str), 575 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.02 (dd, 1H, Ha, Ja,b= 17.4 Hz, Jax= 5.3 Hz), 3.45 (dd, 1H, Hb, Jba= 17.4 Hz, Jbx= 11.7 Hz), 3.51 (s, 2H, CH2), 3.66 (s, 3H, OCH3), 5.48 (dd, 1H, Hx, Jxb= 11.7 Hz, Jxa= 5.3 Hz), 6.37-8.15 (m, 14H, NH and Ar-H), 8.38 (bs, 1H, NH), 9.17 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.51 (CH2), 36.46 (CH2of pyrazole), 55.47 (CH of pyrazole), 112.11-156.26 (24C, Ar-C), 161.12 (C=N of pyrazole), 162.21 (C=O), 167.94 (C=N). Anal. found: C, 50.02; H, 3.21; N, 11.36 %; Calcd. for C31H24Br2Cl2N6O2, C, 50.09; H, 3.25; N, 11.31 %.

2-[2-(2,6-Dichlorophenyl)amino]benzyl-3-[5-(4-methoxyphenyl)-4,5-dihydro-n class="Chemical">1H-pyrazol-3-yl-amino]-6,8-dibromoquinazolin-4(3H)ones (6m)

Yield: 69 %. m.p. 165-167°C. IR (KBr) (cm-1): 3437 (NH str), 2918, 2845 (CH2str), 1718 (C=O str), 1607 (C=N str), 1238, 1105 (C-n class="Chemical">O-C str), 737 (C-Cl str), 562 (C-Br str). 1H-NMR (CDCl3, 400 MHz), δ (ppm): 3.03 (dd, 1H, Ha, Ja,b= 17.5 Hz, Jax= 5.5 Hz), 3.46 (dd, 1H, Hb, Jba= 17.5 Hz, Jbx= 11.8 Hz), 3.52 (s, 2H, CH2), 3.64 (s, 3H, OCH3), 5.49 (dd, 1H, Hx, Jxb= 11.8 Hz, Jxa= 5.5 Hz), 6.36-8.16 (m, 14H, NH and Ar-H), 8.42 (bs, 1H, NH), 9.15 (bs, 1H, NH). 13C-NMR (CDCl3, 100 MHz), δ (ppm): 30.64 (CH2), 36.40 (CH2of pyrazole), 55.42 (CH of pyrazole), 111.85-158.32 (24C, Ar-C), 160.97 (C=N of pyrazole), 162.05 (C=O), 168.02 (C=N). Anal. found: C, 49.96; H, 3.20; N, 11.24 %; Calcd. for C31H24Br2Cl2N6O2, C, 50.09; H, 3.25; N, 11.31 %.

Antimicrobial activity

The in vitro antimicrobial activities of compounds 6a-m were carried out by the cup-plate method.[27] Antibacterial activity was screened against two gram-positive bacteria n class="Species">S. aureus (ATCC 12228) and B. subtilis (ATCC 11778), and two gram-negative bacteria E. coli (ATCC 8739) and Certium (ATCC 27957), by measuring the zone of inhibition on agar plates at two different concentrations 100 μg/ml and 50 μg/ml. While antifungal activity was tested by measuring the zone of inhibition on agar plates with two fungal species C. albicans (ATCC 10231) and A. niger (ATCC 16404) at two different concentrations 20 μg/ml and 10 μg/ml. Penicillin-G was used as a standard antibacterial agent, whereas fluconazole was used as a standard antifungal agent.

RESULTS AND DISCUSSION

The title compounds 2-[2-(2,6-dichlorophenyl)amino]benzyl-3-(5-substituted phenyl-4,5-dihydro -n class="Chemical">1H-pyrazol-3-yl-amino)-6,8-dibromoquinazolin-4(3H)ones 6a-m were synthesized according to described process in Scheme 1. The structures of all the synthesized compounds were elucidated by the elemental analysis as well as IR and NMR spectral data. IR spectra showed strong C=O and C=N stretching of quinazolinone at around 1720 cm-1and 1610 cm-1. The 1H NMR spectra of compounds 6a-m indicated that the -CH2protons of the pyrazoline ring resonated as a pair of doublet of doublets (Ha and Hb) due to geminal and vicinal coupling. The CH proton appeared as a doublet of doublet (Hx) due to vicinal coupling with the two magnetically nonequivalent protons of methylene group at position 4 of pyrazoline ring. The Ha proton which is cis to Hx resonates upfield in the range δ 3.02-3.07 as a doublet of doublet while Hb, the other proton which is trans to Hx resonates downfield in the range δ 3.45-3.49 as a doublet of doublet. The Hx proton which is vicinal to two methylene protons (Ha and Hb) resonates as a doublet of doublet in the range δ 5.46-5.51. In 13C NMR spectra, signals at around δ 36.5, δ 55.5, and δ 161 confirms the presence of CH2, CH, and C=N of pyrazoline ring, respectively, whereas C=O and C=N signals of quinazolinone ring are appear at around δ 162 and δ 168, respectively.

Scheme 1

Synthetic route of compounds 6a-m

The results of antibacterial activity are shown in Table 1. Compounds 6a (R = H) and n class="Chemical">6h (R = 2-NO2) showed good activities against gram-positive bacteria (70.87% and 63.39% against S. aureus respectively; 73.97% and 69.56% against B. subtilis, respectively). The remaining compounds showed moderate activities (44.19-55.29%) against gram-positive bacteria as compared to penicillin-G. Compounds containing para-substituted hydroxyl, chloro and methoxy groups were found active than ortho- and meta-substituted compounds while ortho substituted nitro compound showed good activity than meta- and para-substituted nitro compounds against gram-positive bacteria. Compounds 6h (R = 2-NO2) and 6i (R = 3-NO2) exhibited good activities against gram-negative bacteria (65.04% and 74% against E. coli, respectively; 68.97% and 78.63% against Certium, respectively). The remaining compounds showed moderate activities (37.98-58.63%) against gram-negative bacteria as compared to penicillin-G. Meta-substituted hydroxyl and nitro compounds possessed good activity against gram-negative bacteria as compared to ortho- and para-substituted compounds. Whereas ortho-substituted chloro compound was found good as compared to meta and para, and methoxy group containing compounds share an equal activity against gram-negative bacteria E. coli. On the other hand, ortho-substituted methoxy compound was found good than para-substituted compound and meta-substituted chloro compound showed lower activity as compared to ortho- and para-substituted chloro compound against gram-negative bacteria Certium. Furthermore, compound 6h (R = 2-NO2) was active against all gram positive as well as gram-negative bacteria, while compound 6a (R = H) was active against both gram-positive bacteria and compound 6i (R = 3-NO2) was active against both gram-negative bacteria. Also, compound 6l (R = 2-OCH3) displayed good activity (61.15 %) against gram-negative bacteria Certium. In addition compounds containing dimethylamino group exhibited quite low activity than others against gram-positive as well as gram-negative bacteria.

Table 1

Antibacterial activity of compounds 6a-m

Compound	R	Zone of inhibition (mm)
		S. aureus ATCC 12228			B. subtilis ATCC 11778			E. coli ATCC 8739			Certium ATCC 27957
		CH	CL	Pot. %	CH	CL	Pot. %	CH	CL	Pot. %	CH	CL	Pot. %
6a	H	21	17	70.87	20	16	73.97	12	10	40.08	11	9	41.85
6b	2-OH	15	12	52.83	14	12	50.10	16	13	52.45	15	13	52.40
6c	3-OH	13	10	48.23	12	10	44.19	17	14	55.02	16	13	58.22
6d	4-OH	15	12	52.83	15	13	53.35	16	13	52.45	15	12	55.43
6e	2-Cl	13	10	48.23	12	10	44.19	14	12	44.63	13	11	46.83
6f	3-Cl	13	10	48.23	12	10	44.19	12	10	40.08	11	9	41.85
6g	4-Cl	14	11	50.47	13	11	47.05	13	11	42.30	13	11	46.83
6h	2-NO2	19	16	63.39	19	16	69.56	20	16	65.04	19	15	68.97
6i	3-NO2	15	12	52.83	14	12	50.10	23	19	74.00	22	18	78.63
6j	4-NO2	16	13	55.29	15	13	53.35	17	14	55.02	16	13	58.22
6k	4-N(CH3)2	13	10	48.23	12	10	44.19	11	9	37.98	10	8	39.56
6l	2-OCH3	14	11	50.47	13	11	47.05	18	15	57.71	17	14	61.15
6m	4-OCH3	15	12	52.83	14	12	50.10	18	15	57.71	17	15	58.63
Penicillin		30	25	100	27	21	100	31	25	100	28	23	100

CH = zone of inhibition at 100 μg/ml

CL = zone of inhibition at 50 μg/ml

Pot. = potency in %

The results of antifungal activity are shown in Table 2. Compounds 6d (R = 4-OH), 6e (R = n class="Chemical">2-Cl), 6f (R = 3-Cl), 6g (R = 4-Cl), and 6h (R = 2-NO2) exhibited very good activities (61.84-84.70 %) against C. albicans while compounds 6e (R = 2-Cl), 6f (R = 3-Cl), and 6g (R = 4-Cl) possessed very good activities (63.41-78.57 %) against A. niger as compared to standard drug fluconazole. The remaining compounds showed moderate activities. Compounds 6e (R = 2-Cl) and 6g (R = 4-Cl) exhibited pronounced activities (84.70 % and 80.77 %) against C. albicans among the series. Ortho-substituted chloro and nitro compounds showed good activity as compared to meta- and para-substituted compounds against both C. albicans and A. niger. On the other hand, para-substituted hydroxyl compound was found good against C. albicans as compared to ortho and meta, while meta-substituted hydroxyl compound possessed higher activity against A. niger than ortho- and para-substituted compounds. Both ortho and para-substituted methoxy group containing compounds exhibited same activity against C. albicans and A. niger.

Table 2

Antifungal activity of compounds 6a-m

Compound	R	Zone of inhibition (mm)
		C. albicans ATCC 10231			A. niger ATCC 16404
		CH	CL	Pot. %	CH	CL	Pot. %
6a	H	15	12	58.63	15	13	51.52
6b	2-OH	10	8	41.28	9	7	35.88
6c	3-OH	7	0	49.07	6	0	41.30
6d	4-OH	9	7	68.84	9	7	35.88
6e	2-Cl	22	18	84.70	22	18	78.57
6f	3-Cl	19	16	72.59	18	15	63.41
6g	4-Cl	21	17	80.77	20	16	71.35
6h	2-NO2	16	13	61.84	15	13	51.52
6i	3-NO2	13	11	49.57	12	10	43.00
6j	4-NO2	15	13	56.01	14	12	48.51
6k	4-N(CH3)2	15	13	56.01	15	13	51.52
6l	2-OCH3	7	0	49.07	6	0	41.30
6m	4-OCH3	7	0	49.07	6	0	41.30
Fluconazole		26	21	100	28	22	100

CH = zone of inhibition at 20 μg/ml

CL = zone of inhibition at 10 μg/ml

Pot. = potency in %

CONCLUSIONS

All the compounds showed satisfactory elemental as well as IR and NMR spectral results. Compounds bearing n class="Chemical">2-nitro group showed promising activity against all bacterial species while chloro group-containing compounds were found active against both fungal species. All this findings give ideas to improve antimicrobial activity for further studies.